1. Field of the Invention
In general, the present invention relates to arrays of LEDs that are used for general illumination purposes. More particularly, the present invention relates to LED arrays with diffuser elements that help blend light beams generated by the individual LEDs in the array.
2. Prior Art Description
Light emitting diodes (LEDs) are commercially available in a wide variety of sizes and colors. LEDs are used for many purposes, such as for producing television displays. However, one of the fastest growing uses of LEDs is for general illumination, where LED arrays are being used in place of incandescent light bulbs and fluorescent bulbs. LEDs use less power and last much longer than either incandescent bulbs or fluorescent bulbs. Accordingly, the use of an LED light source is preferable in many lighting applications.
Although LEDs have advantages, they also embody certain disadvantages. In order for LEDs to emit light comparable to an incandescent light bulb or a fluorescent light bulb, an array of LEDs must be used. In an array of LEDs, the LEDs are placed together as close as possible. The density of the LEDs in the array is primarily dictated by the size of the LEDs, the power requirements of the LEDs and the thermal cooling requirements of the LEDs.
The output of an LED is greatly affected by temperature. If an LED becomes too hot, its light output decreases dramatically. If very high power LEDs are used, the LED array may only contain a few individual LEDs. However, the LEDs may have to be spaced relatively far apart so that the heat generated by the individual LEDs can be adequately dissipated.
Florescent bulbs traditionally provide a long strip of bright light. When an LED array is created to replace a florescent light, high powered LEDs are often placed in a straight line. Depending upon the power of the LEDs used, the spacing between the LEDs along the line can be as far apart as an inch.
When high powered LEDs are so widely spaced, they tend to create their own independent beams of light. Consequently, the light under such an LED array is not uniform. Rather, if an LED array has ten linearly aligned lights, for example, the illuminated area under the LED array would tend to have ten bright spots. This effect is often undesirable and causes consumers to opt for traditional florescent lights rather than an LED array.
Some attempts have been made to diffuse light produced by linear arrays of LEDs. U.S. Pat. No. 7,267,459 to Matheson discloses a linear LED array. It is disclosed that the LEDs many be covered with a lenticular lens. However, no details of the lenticular lens are provided, such as orientation, lens density and the like. The use of a diffusing element, such as a lenticular lens diffuses light, however, it also has the adverse effect of reducing light intensity. Many traditional lenticular lenses can absorb or misdirect much of the light energy produced by an LED. Consequently, if traditional lenticular lenses are used, the LEDs must be far more powerful than they need be to produce a desired degree of illumination.
A need therefore exists for a system and method of diffusing the light emitted by an LED array so that light form the LEDs is diffused with a minimum of light energy absorption. This need is met by the present invention as described below.